Regulating arrangement preferably for regulating the temperature in heating systems

ABSTRACT

A regulating arrangement comprises a control signal input bridge having a transistor amplifier connected as a diagonal and an electronic switching device connected in series in the bridge output. Means are operable to vary rhythmically the value of one arm of the bridge, and the resulting bridge diagonal voltage is applied, as a control voltage, to an active element of the bridge controlling the bridge output. One arm of the bridge includes a negative temperature coefficient resistance and the other arm of the bridge includes a resistance whose value is varied rhythmically either by operation of a circuit interrupter or by an electric pulse transmitter.

United States Patent Reuter Mar. 14, 1972 [54] REGULATING ARRANGEMENT3,149,224 9/1964 Home et al. ..2l9/50l UX PREFERABLY FOR REGULATING THE3,281,653 10/1966 Hurley ..307/3l0 X TEMPERATURE [N HEATING SYSTEMS3,504,196 3/1970 Thompson .219/499 X [72] Inventor: Fritz Renter,Esslingen/Neckar, Germany Primary Emminer Roy Lake [73] Assignee: J.Eberspacher, Esslingen/Neckar, Ger- Assis'am Examiner-James Mullins manyAttorney-McGlew and Toren [22] Filed: July 3, 1969 [57] ABSTRACT [2]]Appl' 838736 A regulating arrangement comprises a control signal inputbridge having a transistor amplifier connected as a diagonal [30]Foreign Application Priority Data and an electronic switching deviceconnected in series in the bridge output. Means are operable to varyrhythmically the Oct. 4, 1968 Germany ..P 18 01 158.0 value of one am ofthe bridge, and the resulting bridge 52 us. Cl .307 310 219 499, 328/3,"wage is applied as a Wage m an-active I 1 l 330/146 element of thebridge controlling the bridge output. One arm [5 1] Int. Cl. ..G05d23/24 the bridge includes a negative temperature coefficient [58 1 Fieldof Search ..307/310; 328/3; 330/146; sistance and the other arm of thebridge includes a resistance 219/499, 501 whose value is variedrhythmically either by operation of a circuit interrupter or by anelectric pulse transmitter. 56 R fe euces Cited 1 e r 21Claims,4DrawingFigures UNITED STATES PATENTS 1,927,846 9/1933 Rathgag/r5 v PULSE 'OPERATED ELECTRIC ELEMENT ulse Iunsmdler 4 PATENTEDMAR14 I972 SHEET 1 [IF 2 OPERATED ELECTRIC ELEMENT PULSE- FIG! ELECTRICELEMENT PULSE -OPERHTED FIG. 2

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INVENTOR. FRITZ REUTER A TTORNE'YS REGULATING ARRANGEMENT PREFERABLY FORREGULATING THE TEMPERATURE IN HEATING SYSTEMS BACKGROUND OF THEINVENTION A known regulating arrangement comprises an input bridge witha transistor amplifier arranged in the bridge diagonal and with aseries-connected electronic switching device. An electric resistance isvaried in dependence on mechanical or thermodynamic quantities so thatan electrical or electronic system, connected in series with theregulating arrangement, is influenced. Such a regulator is particularlysuitable for temperature regulation, for example, in heating systems. Inthese heating systems, the object is to regulate the supply of fuel orelectric power or both in dependence on the desired temperature.

Hitherto this has been effected by providing the regulators withvoluminous feedback and compensation elements in order to avoidhysteresis, that is, differences between the response point and the droppoint. However, known arrangements have the considerable disadvantagethat they are not only complicated in their'circuit arrangement but alsothey react over-critically, due to the internal temperature range of theregulator proper. The closer the response, or cut-in" point can be heldto the drop or cutout" point, the better is the regulation effected.

SUMMARY OF THE INVENTION This invention relates to a bridge-typeregulating arrangement for controlling a function in accordance with aninput signal and, more particularly, to a novel and improved inputbridge type regulating arrangement in which the value of one arm of thebridge is varied rhythmically and the response or cut-in point iscoincident with the drop or cutout point.

In accordance with the invention, the regulating arrangement comprisesan input bridge having a transistor amplifier arranged in a bridgediagonal, and having an electronic switching device connected in serieswith the bridge output. Means are provided to vary the value of onebridge arm of the bridge connection rhythmically with the resultingbridge diagonal voltage being applied as a control voltage to an activeelement. The effect of the invention arrangement is that it is possible,for the first time in regulator design, to attain a difference betweenresponse and drop of the series-connected switching part with theaccuracy of and without using feedback circuits and the like. Inaddition, it permits a very stable coupling of the series-connectedelectronic switch, for example, which switches are electrically verystable. In turn, this means a great reduction in the number of partsrequired for the regulating arrangement.

In accordance with the invention, it has been found expedient to connectthe base of the transistor amplifier in a bridge arm which comprises avariable resistance and a temperature-dependent resistance, and toconnect the emmitter of the transistor amplifier to another bridge armincluding a resistance whose value is variable by an interruptor.Furthermore, the collector of the transistor amplifier is connected inthe input of a series-connected electronic switching device. Therhythmic mistuning of the resistance bridge can be effected by anauxiliary voltage or, in accordance with a variation of the invention,the variation in the value of the bridge arm can be effected by anelectric, separately controlled element. In this regulating arrangementof the invention, the impedances of the bridge can be resistive,reactive, or active.

It has been found to be advantageous if the electric pulses, generatedat the output of the electronic switch in the rhythm of the mistunedinput bridge, can be integrated, for example, by an R-C member. As analternative, the pulses generated at the output of the electronic switchin the rhythm of the mistuned input bridge, can actuate a pulse-operatedelectric element, for example, a pump. This last-mentioned expedient, inparticular, plays a preferred role in the use of the regulatingarrangement in connection with heating systems.

An object of the invention is to provide an improved and simplifiedregulating arrangement including a control signal input bridge.

Another object of the invention is to provide such a regulatingarrangement including a transistor amplifier connected as a diagonal ofthe bridge.

A further object of the invention is to provide such a regulatingarrangement including an electronic switching device connected in seriesin the bridge output.

Another object of the invention is to provide a regulating arrangementincluding means operable to vary rhythmically the value of one arm ofthe bridge.

A further object of the invention is to provide such a regulatingarrangement in which the resulting bridge diagonal volt age is applied,as a control voltage, to an active element of the bridge, controllingthe bridge output.

For an understanding of the principles of the invention, reference ismade of the following description of typical embodiments thereof asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIGS. 1 and 2 are schematic wiring diagrams of first and secondembodiments of the regulating arrangement in accordance with theinvention;

FIG. 3 is a diagram graphically illustrating the operation of a knownregulator which does not have any mistuning device for the input bridge;and

FIG. 4 is diagram graphically illustrating the operation of a regulatingarrangement embodying the invention in such a manner that the differencebetween the cut-in and cutout points is zero.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematicallyillustrates a regulating arrangement whose input is formed by a bridgeconnection. A first arm of the bridge is formed by an adjustableresistance R, and a negative temperature-dependent resistance R,,. Thebase B of a transistor amplifier T, is connected to the junction pointof resistances R, and R The second bridge arm is formed by a fixedresistance R, which is connected in series with a parallel combinationof fixed resistances R, and R an interruptor f being connected in serieswith resistance R,.

Resistance R, is a very low ohmic resistance as compared with resistanceR The only function of resistance R, is to act as a protectiveresistance in order to limit the control voltage U,,,, in case ofblockage. The emitter E of the transistor amplifier T, is connected tothe common junction point of resistances R R and R Thus, the diagonalvoltage of the bridge forms the control voltage of the bridge transistoramplifier.

Collector C of transistor amplifier T, is in series with a collectorresistance R, which forms, at the same time, the input resistance forthe switching and threshold value amplifier or switch 1. The switch f isoperable to mistune the bridge with a perfectly constant frequency. Thecontrol voltate U on the transistor amplifier T, between base B andemitter E is thus also varied. With a sufficiently high control volate Uon transistor T,, transistor T, becomes conductive so that a voltagedrop appears across resistance R, by virtue of the collector current ofthe transistor amplifier. In turn this voltage either operates switch 1or does not operate switch I depending on the magnitude of the voltagedrop.

The output of electronic switch 1, in FIG. 1, is represented by a relay2 having a charging condenser 3 connected in parallel therewith. Theratio of the resistance of relay 2 and charging condenser 3 is soselected that relay 2 will not drop when supplied with pulsesuninterruptedly. The relay controls a pulse-actuated electric element 10such as a pump.

FIG. 2 schematically illustrates a regulator which has the sameconstruction as that of FIG. 1. In FIG. 2 resistance R, is

replaced by a switching transistor T which is controlled by a mechanicalor electrical pulse transmitter 4.

FIG. 3 graphically demonstrates how a normal regulator, having no bridgemistuning device, works. The control voltage U for the transistoramplifier is plotted as a function of a negative temperature-dependentresistance. It can be seen from FIG. 3 that, for the threshold value ofthe switch, there is a difference between the input voltage U, and theoutput voltage U This is generally called the hysteresis and is equal toAU so that a connecting and disconnecting potential difference appearsat the temperature At.

FIG. 4 graphically illustrates how the unavoidable hysteresis of theswitching amplifier can be eliminated so that U,,,,=At= can be attained.Due to the fact that the voltage U in FIG. 2 can be raised to theregulating line 2 with control transistor T conducting, and thensubstantially instantaneously lowered to the value 0, there is such arapid passage through the hysteresis range of the switching amplifierthat U, and U coincide in practice.

The invention arrangement has the effect that the on point and off pointfor the regulator coincide without the use of complicated feedback andcompensating parts. Thus, the point of connection of the regulator isidentical with the disconnecting point of the regulator. This, in turn,has a result that only the connecting point is used for regulation,since the threshold value more or less returns to a starting positiondue to the rhythmic influence of the measuring element.

What is claimed is:

1. A regulator for responding to a varying value, comprising bridgemeans having four arms and a diagonal, amplifier means having an inputcircuit forming the diagonal of said bridge means, output meansconnected to said amplifier means to respond thereto, input means forexhibiting a variable electrical value corresponding to the value towhich the regulator responds and in one of the arms, and circuit meansforming a second of said arms for repetitively varying the balance ofsaid bridge means at a rate greater than the variation of the value ofsaid input means.

2. A regulator as in claim 1, wherein said circuit means varies theimpedance of the second arm.

3. A regulator as in claim 1, wherein said circuit means includespulse-generating means having a repetition rate greater than the rate atwhich the value of said input means varies.

4. A regulator as claim 2, wherein said circuit means includespulse-generating means having a repetition rate greater than the rate atwhich the value of said input means varies.

5. A regulator as in claim 1, wherein said input means includes atemperature-sensitive element.

6. A regulator as in claim 4, wherein said input means includes atemperature-sensitive element.

7. A regulator as in claim 1, wherein said circuit means includes animpedance and repetitive switch means for varying the impedance from onevalue to another.

8. A regulator as in claim 7, wherein said impedance includes tworesistors, and said switch means repetitively switches one of saidresistors into and out of parallel arrangement with the other.

9. A regulator as in claim 7, wherein said impedance includes a resistorand network means for repetitively shunting said resistor.

10. A regulator as in claim 3, wherein said circuit means includes animpedance and repetitive switch means for varying the impedance from onevalue to another.

11. A regulator as in claim 3, wherein said impedance includes aresistor and network means for repetitively shunting said resistor.

12. A regulator as in claim 5, wherein said circuit means includes animpedance and repetitive switch means for varying the impedance from onevalue to another.

13. A regulator as in claim 5, wherein said impedance includes aresistor and network means for repetitively shunting said resistor.

14. A regulator as in claim 1, wherein said output means includeselectrical integrating means.

15. A regulator as 111 claim 5, wherein said output means includeselectrical integrating means.

16. A regulator as in claim 9, wherein said output means includesintegrating means for integrating intermittent voltages.

17. A regulator as in claim 16, wherein said integrating means includesa relay.

18. A regulator as in claim 5, wherein said output means includes arelay and means for maintaining a voltage across said relay in responseto repetitive voltage applied across said relay.

19. A regulator as in claim 5, wherein said output means includes apulse-operated electric element, responsive to voltages applied theretoand integrating means for maintaining the voltage applied across saidpulse-operated electric element.

20. A regulator as in claim 1, wherein said circuit means includes asemiconductor device having a main path of current flow connected in thesecond arm and a pulse generator connected to said semiconductor device.

21. A regulator as in claim 1, wherein said output means includes athreshold value switch.

1. A regulator for responding to a varying value, comprising bridgemeans having four arms and a diagonal, amplifier means having an inputcircuit forming the diagonal of said bridge means, output meansconnected to said amplifier means to respond thereto, input means forexhibiting a variable electrical value corresponding to the value towhich the regulator responds and in one of the arms, and circuit meansforming a second of said arms for repetitively varying the balance ofsaid bridge means at a rate greater than the variation of the value ofsaid input means.
 2. A regulator as in claim 1, wherein said circuitmeans varies the impedance of the second arm.
 3. A regulator as in claim1, wherein said circuit means includes pulse-generating means having arepetition rate greater than the rate at which the value of said inputmeans varies.
 4. A regulator as claim 2, wherein said circuit meansincludes pulse-generating means having a repetition rate greater thanthe rate at which the value of said input means varies.
 5. A regulatoras in claim 1, wherein said input means includes a temperature-sensitiveelement.
 6. A regulator as in claim 4, wherein said input means includesa temperature-sensitive element.
 7. A regulator as in claim 1, whereinsaid circuit means includes an impedance and repetitive switch means forvarying the impedance from one value to another.
 8. A regulator as inclaim 7, wherein said impedance includes two resistors, and said switchmeans repetitively switches one of said resistors into and out ofparallel arrangement with the other.
 9. A regulator as in claim 7,wherein said impedance includes a resistor and network means forrepetitively shunting said resistor.
 10. A regulator as in claim 3,wherein said circuit means includes an impedance and repetitive switchmeans for varying the impedance from one value to another.
 11. Aregulator as in claim 3, wherein said impedance includes a resistor andnetwork means for repetitively shunting said resistor.
 12. A regulatoras in claim 5, wherein said circuit means includes an impedance andrepetitive switch means for varying the impedance from one value toanother.
 13. A regulator as in claim 5, wherein said impedance includesa resistor and network means for repetitively shunting said resistor.14. A regulator as in claim 1, wherein said output means includeselectrical integrating means.
 15. A regulator as in claim 5, whereinsaid output means includes electrical integrating means.
 16. A regulatoras in claim 9, wherein said output means includes integrating means forintegrating intermittent voltages.
 17. A regulator as in claim 16,wherein said integrating means includes a relay.
 18. A regulator as inclaim 5, wherein said output means includes a relay and means formaintaining a voltage across said relay in response to repetitivevoltage applied across said relay.
 19. A regulator as in claim 5,wherein said output means includes a pulse-operated electric element,responsive to voltages applied thereto and integrating means formaintaining the voltage applied across said pulse-operated electricelement.
 20. A regulator as in claim 1, wherein said circuit meansincludes a semiconductor device having a main path of current flowconnected in the second arm and a pulse generator connected to saidsemiconductor device.
 21. A regulator as in claim 1, wherein said outputmeans includes a threshold value switch.